Battery change apparatus and method for a locomotive remote control system

ABSTRACT

A remote control system ( 10 ) for a locomotive ( 14 ) having a auxiliary power source ( 42 ) in the operator control unit (OCU) ( 16 ) so that the unique communications link identifier stored in the volatile memory ( 40 ) of the OCU is not lost during change-out of the OCU main battery ( 22 ). A method ( 20 ) for changing the OCU main battery ( 22 ) may include the step of entering a power saving mode ( 54 ) while operating on the auxiliary power source. The locomotive is maintained in a safe condition without unlinking from the OCU for a predetermined time interval ( 66 ) until full power is re-established using the refreshed battery in the OCU. In one embodiment, auxiliary power may be provided by one of two batteries ( 72, 74 ) in the OCU while the other of the two batteries is being changed. A sliding panel ( 78 ) may be used to allow only one battery to be removed from the OCU at a time.

[0001] This application claims the benefit of U.S. Provisional Application No. 60/365,634 filed Mar. 19, 2002.

FIELD OF THE INVENTION

[0002] This invention relates generally to the field of rail transportation, and more particularly to a remote-control system for a locomotive.

BACKGROUND OF THE INVENTION

[0003] It is known to remotely control a locomotive using a handheld operator control unit (OCU) that is in radio communication with associated slave equipment onboard the locomotive. Such units are often used in a switching yard where assemblies of railcars and locomotives are coupled together to form trains. Such units may also be used in an industrial application where a locomotive is used to deliver railcars filled with various materials to multiple locations within a plant site. One such system is available from Canac Inc. and is described in Canac's U.S. Pat. Nos. 5, 511,749 and 5,685,507. Another remote control system is offered by Cattron-Thiemeg, Inc.

[0004] Remote-control systems for locomotives rely on a two-way radio communications link between the operator control unit and the onboard equipment. Command signals are input to the OCU by the operator in the form of the movement of a switch, lever, dial, etc. The command signal is converted to an electromagnetic signal that is transmitted from the OCU to an onboard receiver. The received electromagnetic command signal is then converted into an appropriate control action by an onboard servomechanism. Signals may also be initiated by onboard equipment and transmitted back to the OCU for display to the operator to report the status of onboard systems. The signals transmitted to control a locomotive typically comprise a binary locomotive status word that represents the requested operative state of the locomotive being controlled. One such locomotive radio control system incorporating transmission of binary locomotive status words to remotely communicate with a locomotive is sold under the trademark Beltpack™ by Canac, Inc. of Montreal, Canada.

[0005] The quality and security of the radio communication link between the OCU and the onboard equipment are critical for safe, reliable remote control of the locomotive. Importantly, the locomotive must respond only to signals initiated by the locomotive operator's OCU and not to spurious radio signals generated by other sources, including other OCU's operating in the same area. To ensure the integrity of the radio communication link, it is known for the OCU and the onboard equipment to communicate by using a unique link identifier. The link identifier is an electronic code, stored in volatile memory in the OCU that uniquely represents the transmitter designated to control the locomotive. Whenever a command is transmitted to a designated locomotive, the link identifier is retrieved from volatile memory and appended to the locomotive status word that is then transmitted to the onboard receiver. In addition, the transmitter can be programmed to repetitively transmit the locomotive status word at a fixed rate. By providing the transmitter with a unique repetition rate, the likelihood of transmission errors is reduced when several portable transmitters in close proximity broadcast control signals to individual locomotives.

[0006] To initialize the OCU link identifier to communicate with a designated locomotive, the operator boards the locomotive with the OCU to execute a linking procedure that enters the unique locomotive identifier into the OCU volatile memory. Once the identifier has been downloaded to the OCU volatile memory, the onboard remote control equipment will then respond to radio control signals that are encoded with the correct link identifier. For each transmitted locomotive status word received by the locomotive, the onboard receiver extracts the identifier code embedded in the status word and verifies that the received identifier code matches the code of a remote transmitter designated to control the receiving locomotive. This ensures that only the intended OCU will have control over the locomotive. As a safety measure, the onboard equipment is programmed to place the locomotive in a safe condition (stopped and brakes applied) if no properly linked communication is received from the OCU within a predetermined time period.

[0007] Because they are intended to be portable devices, the operator control units are powered by batteries. The batteries have a useful charge life and they must be recharged or replaced with fresh batteries periodically. Most locomotive remote control systems include a sophisticated microprocessor-based power level sensor that accurately predicts the remaining battery life for the OCU. This information allows the operator to avoid a situation where the remote control system fails unexpectedly due to a low battery charge condition. When the remaining charge life of the batteries drops below a predetermined limit, the batteries are changed in an orderly manner at the convenience of the operator. However, the change-out of batteries causes a break in the radio communication link between the OCU and the locomotive, and it deletes the link identifier from the OCU volatile memory.

[0008] Once the new batteries are installed, the secured communication link must be reestablished. This necessitates the operator boarding the locomotive to execute the linking procedure to re-enter the unique locomotive identifier into the OCU volatile memory. This may result in an extended delay, since the locomotive may be located as far as ½ mile away from the operator's location.

[0009] It is known in the art to “hot-swap” batteries in electronic devices. Systems such as laptop computers typically incorporate hot swapping features to allow refreshing batteries without requiring system shut down. One such system is described in U.S. Pat. No. 5,832,282. However, prior art hot-swapping solutions do not address the problem of maintaining a communication link when a battery changeover is required.

BRIEF SUMMARY OF THE INVENTION

[0010] A method for refreshing a power source in a portable operator control unit (OCU) used for remotely controlling the operation of a locomotive is described herein as including: operating an OCU with a first power source to control a locomotive over a communication link characterized by a unique identifier; and switching the operation of the OCU from the first power source to a second power source without losing the unique identifier so as to maintain the communication link with the locomotive. The step of switching may include providing power from the second power source to a volatile memory storing the unique identifier so that the volatile memory is not erased while the first power source is being refreshed.

[0011] A system is described for hot-swapping power sources in a locomotive remote control system, wherein a portable operator control unit (OCU) is in communication with a receiver on a locomotive being remotely controlled over a communication link comprising a unique identifier stored in a volatile memory of the OCU, the system including: a first power source; a second power source; and a circuit for providing power to the OCU from the second power source so that the communication link with the locomotive is maintained while the first power source is being refreshed. The system may further include a circuit for providing power from the second power source to a volatile memory portion of the OCU storing the unique identifier while the first power source is being refreshed. The second power source may be one of a capacitor, a long-term storage battery and a solar panel. The system may further include: two batteries each capable of powering the OCU; and a mechanism limiting physical access to only one of the two batteries at a time. The system may further a switch responsive to a position of the mechanism for switching the source of power for the OCU from a first of the two batteries to a second of the two batteries. The mechanism may be a sliding panel in a battery compartment of the OCU.

[0012] A remote control system for controlling a locomotive is described herein as including comprising: a controller onboard a locomotive for controlling the locomotive in response to a remote control signal comprising a unique identifier; an operator control unit (OCU) remote from the locomotive for generating the remote control signal, wherein the OCU further comprises: a first power source; a second power source; and a circuit for providing power to a volatile memory portion of the OCU from the second power source to maintain the unique identifier in the volatile memory while the first power source is being refreshed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The features and advantages of the present invention will become apparent from the following detailed description of the invention when read with the accompanying drawings wherein:

[0014]FIG. 1 illustrates a locomotive being remotely controlled by a handheld operator control unit.

[0015]FIG. 2A is a functional block diagram of component parts of the operator control unit of FIG. 1.

[0016]FIG. 2B is a functional block diagram of the locomotive onboard controller of FIG. 1.

[0017]FIG. 3 illustrates a method of changing the battery of the operator control unit of FIG. 2A without losing the communication link between the OCU and the locomotive onboard equipment.

[0018]FIG. 4 illustrates the battery compartment of an operator control unit having a device that allows the change-out of only one of two batteries at a time.

[0019] In certain situations for reasons of computational efficiency or ease of maintenance, the ordering of the blocks of the illustrated flow charts could be rearranged or moved inside or outside of the illustrated loops by one skilled in the art. While the present invention will be described with reference to the details of the embodiments of the invention shown in the drawing, these details are not intended to limit the scope of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention allows the operator of a remotely controlled locomotive to replace discharged batteries in a handheld operator control unit (OCU) without losing the communication link with the locomotive, so that the operator does not have to board the locomotive to re-perform the linking operation of reloading the volatile memory of the OCU unit with the unique locomotive identifier. The present invention retains the safety feature that when the communication link between the OCU and the locomotive is lost for reasons other than a battery change-out or recharging, the locomotive will automatically come to a safe stop and will unlink. For the case where an operator intentionally changes out the OCU batteries, the communication link is maintained during the battery change-out process until normal operating conditions are reestablished.

[0021]FIG. 1 illustrates a remote control system 10 being used by an operator 12 to remotely control a locomotive 14. The remote control system 10 includes a handheld battery-powered operator control unit (OCU) 16 in radio communication with communication and control equipment 18 located onboard the locomotive 14. To initiate remote control operation, the operator 12 must board the locomotive designated to be controlled and perform a linking operation between the OCU 16 and the control equipment 18 mounted on the locomotive 14. During the onboard linking process, the operator downloads the unique locomotive identifier into the volatile memory of the OCU 16.

[0022] The downloaded unique identifier is thereafter included in commands transmitted to the designated locomotive 14 so that the locomotive control equipment 18 can identify the source of the command by the associated unique identifier and respond appropriately. Once the unique identifier is downloaded, radio communication with the locomotive is established. The radio link thus established will be maintained provided the unique identifier code remains in volatile memory and the communication link is not broken.

[0023]FIG. 2A is a functional diagram of component parts of the operator control unit 16 of FIG. 1. OCU 16 includes a main computer processing unit (CPU) 24 that is normally powered by battery 22. CPU 24 receives control input signals 26 from various operator-actuated control input devices 28. The CPU 24 controls the function of radio transmitter 30 to broadcast electromagnetic signals 32 to the onboard equipment 18. In an embodiment, the electromagnetic signals 32 comprise a locomotive status word encoded to provide control information. CPU 24 is programmed to intelligently assemble the locomotive status word by continuously scanning the electric contacts of the control input devices 28 and recording their settings. Based on the scanned input device 28 settings, the CPU 28 constructs a locomotive status word that is a string of bits uniquely representing the functions to be performed by the controlled locomotive 14.

[0024] Receiver 34 receives electromagnetic signals 36 from the onboard equipment 18 for processing by the CPU 24 and display of status information on operator display 38. A volatile memory 40 is associated with CPU 24 and is used to store a unique link identifier for establishing exclusively linked communication with onboard equipment 18. For example, the unique identifier may be the identification number of the locomotive, the serial number of the locomotive, or any identifier that is uniquely assigned to and associated with a specific locomotive 14. In an aspect of the invention, the unique identifier may be an encoded identifier to provide a secure link between the locomotive onboard equipment 18 and the OCU 16. In an embodiment, the unique link identifier is retrieved from volatile memory and appended to each locomotive status word transmitted to a target locomotive 14 to uniquely identify the transmitter designated to control the locomotive 14. The purpose of this feature is to ensure that the locomotive will only accept the commands issued by the transmitter generating the proper identifier. Loss of electrical power to the CPU 24, however, results in the loss of the link identifier from the volatile memory 40. The CPU 24 will be unable to retrieve a valid unique identifier from volatile memory, and subsequent transmissions will lack the required unique identifier. Consequently, in the absence of a unique identifier, the target locomotive 14 will not recognize a received remote control command.

[0025] To prevent the loss of information stored in volatile and memory and the resulting loss of the communication link, OCU 16 is also provided with a supply of auxiliary power 42. This auxiliary power supply 42 may be a small long-term storage battery, such as a lithium cell, a charged capacitor, or a solar panel, etc. Optimally, the power storage capacity of the supply of auxiliary power 42 need only be a small fraction of the power storage capacity of battery 22 since power is drawn from the supply of auxiliary power 42 during only a short period when battery 22 is being changed.

[0026] The CPU 24 and other components of the OCU 16 may be powered by either the battery 22 or the auxiliary power 42 depending upon the state of a switching device, such as switch 44. In addition, a battery power monitor 23 monitors the condition of the battery 22 and provides an available power indication to the CPU 24. When the available power from the battery reaches a predetermined level, an indication is provided to an operator, such as activating a light emitting diode (LED) 39 on the OCU 16 or providing an indication in the display 38. Optionally, an auxiliary power monitor 43 monitors the condition of the auxiliary power 42 and provides an available auxiliary power 42 indication to the CPU 24. When the available power from the auxiliary power 42 reaches a predetermined level, an indication is provided to an operator, such as activating the LED 39 on the OCU 16 or providing an indication in the display 38.

[0027] When the CPU 24 indicates a low power condition, a switch 44 is provided to allow an operator to select the source of power supplied to the OCU 16. When an operator recognizes a low power indication, the operator sets the switch 44 to an auxiliary power position to provide power from the auxiliary power source 42 before changing or refreshing the battery 22. After installing a new battery 22 or recharging the battery 22, the operator can set the switch 44 to a primary power position to select providing power to the OCU 16 from the battery 22. In an alternative embodiment, the switching device detects impending removal of the battery 22, such as a switch operably connected to a battery access cover. When an operator opens the battery access cover, the switching device is activated and switches the power supplied to the OCU 16 from the battery 22 to the auxiliary source 42. When the battery is reinstalled 22 and the access cover replaced, the switching device detects the replacement of the access cover and switches the power supplied to the OCU 16 from the auxiliary source 42 back to the refreshed battery 22. In yet another embodiment, the processor is programmed to automatically switch power when the battery's 22 power output declines below a predetermined minimum power output level. The processor, receiving inputs from the battery power monitor 23, detects a low power condition in the battery and automatically commands the switch 44 to switch power supplied to the OCU 16 from the battery 22′ to the auxiliary source 42, until the battery 22 is refreshed.

[0028] In addition to the above described switch embodiments, the CPU 24 can be programmed to provide failsafe modes to prevent accidental loss of power, such as an operator-ignored low battery condition or accidental removal of the battery 22 or auxiliary power source 42. For example, if an operator has set the manual switch to auxiliary power, removes the battery 22, and accidentally sets the switch to primary power while the battery 22 is removed, the CPU 24 can be programmed to override the switch 44 setting if the battery 22 is not present. The CPU 24 detects the absence of the battery by receiving a “no power” indication from the battery power monitor 23 when the battery is removed 22.

[0029]FIG. 2B is a functional block diagram of the locomotive onboard controller of FIG. 1. The control equipment 18 located onboard the locomotive 14 includes a receiver 19, a CPU 20, and a timer circuit 21. In an embodiment, the timer circuit 21 times the duration that the locomotive is instructed to remain in a safe condition, such as when the OCU 16 battery 22 is being refreshed. The CPU 20 instructs the timer circuit 21 to start timing when a safe mode command is received. The timer circuit 21 provides time information to the CPU 20, stops timing when a predetermined time period is exceeded, and provides the CPU 20 with an indication that the predetermined time period has been exceeded. The CPU 20 processes the timer circuit 21 information according to programmed timeouts. For example, if the time duration in the safe mode exceeds a preset time, the CPU 20 commands the locomotive onboard equipment 18 to unlink communications with the OCU 16. Alternatively, if the time in the safe mode exceeds a preset time, the CPU 20 commands the locomotive onboard equipment 18 to ignore transmission from the OCU 16, even if the link remains active. In both cases, when the predetermined safe mode time period is exceeded as determined by the timer circuit 21, the operator of the OCU 16 must re-board the locomotive to re-link the OCU 16 to the onboard equipment.

[0030]FIG. 3 illustrates a method 45 for changing the battery 22 of the OCU 16 without losing the communication link between the OCU 16 and the onboard equipment 18. Upon an indication of a low charge level in battery 22, or at any time selected by the operator, the remote control system 10 may be placed in a battery change mode at step 46. This may be accomplished by energizing a special switch 44 on OCU 16, by activating a routine of programmed instructions stored in CPU 24, or automatically, according to programmed instructions stored in CPU 24. Upon entering the battery change mode at step 46, a safe mode signal is sent from the OCU 16 to the onboard equipment 18 in step 47 to place the locomotive 14 in a safe condition. The onboard equipment 18 receives the signal in step 48 and places the locomotive the in a safe condition, or safe mode, at step 50. In this condition the onboard equipment 18 will not unlink even if the radio signal 32 from the OCU 16 is temporarily lost, as described below.

[0031] After the onboard equipment 18 locomotive has been instructed to place the locomotive in safe mode, the power source for the OCU 16 is changed from the battery 22 to the auxiliary power source 42 at step 52. To reduce the necessary capacity of the auxiliary power source 42, the OCU 16 may be placed in a power save mode at step 54 either before or after being connected to the auxiliary power supply 42. Even in the power saving mode, power is maintained to at least the volatile memory 40 so that the stored link identifier is not lost. Alternatively, in the power saving mode, power is provided to the entire transmitter portion of the OCU 16 to maintain the communication link with the locomotive control equipment 18, with other power requirements dropped temporarily to reduce the power draw during the battery change-out period.

[0032] Battery 22 is then changed out to install a fully charged battery 22′ at step 56. Battery power is restored as the power source for the OCU 16 at step 58, and power save mode is exited at step 60. Once full power is restored to the OCU 16, battery change mode is exited at step 62 and if the communication link is operative in step 63, full control of the locomotive 14 is regained by the OCU 16 at step 64. If the communication link has been unlinked in step 63, then the link must be reestablished 65 by the operator by boarding the locomotive to perform the re-linking procedure, a step that is to be avoided by the system and method of the present invention.

[0033] During the battery change mode procedure (steps 52 to 62), the onboard equipment 18 will instruct the locomotive 14 to remain in the safe condition without unlinking from the OCU 16, provided a predetermined time period, indicated by “X,” is not exceeded at step 66. A safe mode timer circuit 21 is provided as part of the battery change mode onboard equipment 18 to time the period the locomotive is in safe mode. If control of the locomotive 14 has been regained (in step 64) before the time period is exceeded at step 68, then the onboard equipment 18 will recognize and respond to OCU 16 commands in step 69. If control of the locomotive 14 has not been regained at step 68 prior to the end of the predetermined time period, the onboard equipment 18 will unlink at step 70 and the operator will have to re-board the locomotive to re-establish remote control operation. This option is provided as a safeguard in the event that battery refreshing can not be completed satisfactorily for any reason.

[0034]FIG. 4 illustrates an alternative method and system for providing an auxiliary power supply 42. The OCU 16 may be provided with two batteries 72, 74. Batteries 72, 74 are installed in a battery compartment 76 of an OCU. Battery 74 is illustrated in phantom in FIG. 4 because it is hidden from view behind a sliding panel 78. Sliding panel 78 is one embodiment of a device that permits only one of a plurality of batteries to be changed at a time. A regulated power supply in the OCU 16 may permit the remote control system 10 to be operated with an OCU battery voltage varying over a wide range, such as from 3-14 volts. In one embodiment, two 6 volt batteries 72, 74 are provided and the power output of each battery 72, 74 is monitored. Once the charge level in the batteries 72, 74 drops to a predetermined level as indicated by the power monitor, the battery change procedure 45 of FIG. 3 is implemented. In this embodiment, the auxiliary power is provided by operating the OCU 16 with just one of the two batteries 72, 74. The amount of power supplied is sufficient to at least maintain electrical power to volatile memory 40 so that the stored link identifier is not lost. Alternatively, the amount of power supplied is sufficient to at least maintain electrical power to transmitter 34 to maintain the communication link. Battery 72 is changed out with sliding panel 78 moved to a position directly over battery 74. Once battery 72 is refreshed, sliding panel 78 is moved directly over battery 72 and battery 74 is changed out. After both batteries 72, 74 are changed, full power and normal operation are restored using both refreshed batteries 72, 74. This procedure allows the communication link to be maintained and prevents loss of the unique identifier from volatile memory 40.

[0035] In another embodiment, OCU 16 is operated on one battery 72 of a two battery 72, 74 pair until battery 72 is nearly depleted as indicated by the power monitor. Power draw is then switched to a second battery 74 of the two battery 72, 74 pair. This power source change may be accomplished by the actuation of a switch moved in conjunction with the movement of sliding panel 78. Battery 72 may then be changed out at the convenience of the operator at any time before the charge in battery 74 is depleted. In this manner, battery power to OCU 16 may be refreshed during operation of remote control system 10 without the loss of the stored unique link identifier, without loss of the communication link, and without the need for the operator 12 to re-board the locomotive 14.

[0036] While the preferred embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions will occur to those of skill in the art without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims. 

We claim as our invention:
 1. A method for refreshing a power source in a portable operator control unit (OCU) used for remotely controlling the operation of a locomotive, the method comprising: operating an OCU with a first power source to control a locomotive over a communication link characterized by a unique identifier; and switching the operation of the OCU from the first power source to a second power source without losing the unique identifier so as to maintain the communication link with the locomotive.
 2. The method of claim 1, wherein the step of switching comprises providing power from the second power source to a volatile memory storing the unique identifier so that the volatile memory is not erased while the first power source is being refreshed.
 3. The method of claim 1, further comprising providing power from the second power source to a transmitter portion of the OCU while the first power source is being refreshed to allow the transmitter portion to maintain the communication link.
 4. The method of claim 1, further comprising sending a signal to the locomotive to put the locomotive in a safe mode prior to the step of switching.
 5. The method of claim 1, further comprising providing one of a capacitor, a long-term storage battery, and a solar panel as the second power source.
 6. The method of claim 1, wherein the OCU comprises two batteries each capable of powering the OCU, the method further comprising: switching the source of power for the OCU from a first of the batteries to a second of the batteries in response to movement of a mechanism that limits access to only one of the two batteries at a time.
 7. The method of claim 1, further comprising: monitoring a condition of the first power sources; and switching operation of the OCU from the first power source to the second power source when the condition reaches a predetermined level.
 8. The method of claim 1, further comprising allowing transmission from the OCU to the locomotive to be suspended for a predetermined time period during the step of switching without interrupting the communication link.
 9. A system for hot-swapping power sources in a locomotive remote control system, wherein a portable operator control unit (OCU) is in communication with a receiver on a locomotive being remotely controlled over a communication link comprising a unique identifier stored in a volatile memory of the OCU, the system comprising: a first power source; a second power source; and a circuit for providing power to the OCU from the second power source so that the communication link with the locomotive is maintained while the first power source is being refreshed.
 10. The system of claim 9, further comprising a circuit for providing power to a transmitter portion of the OCU from the second power source while the first power source is being refreshed.
 11. The system of claim 9, further comprising a circuit for providing power from the second power source to a volatile memory portion of the OCU storing the unique identifier while the first power source is being refreshed.
 12. The system of claim 9, wherein the second power source comprises one of a capacitor, a long-term storage battery and a solar panel.
 13. The system of claim 9, further comprising: two batteries each capable of powering the OCU; and a mechanism limiting physical access to only one of the two batteries at a time.
 14. The system of claim 13, further comprising a switch responsive to a position of the mechanism for switching the source of power for the OCU from a first of the two batteries to a second of the two batteries.
 15. The system of claim 13, wherein the mechanism comprises a sliding panel in a battery compartment of the OCU.
 16. The system of claim 9, further comprising a timer circuit for unlinking the communications link if the first power source is not refreshed within a predetermined time period.
 17. The system of claim 9, further comprising a failsafe mode preventing inadvertent loss of power to the OCU.
 18. A remote control system for controlling a locomotive comprising: a controller onboard a locomotive for controlling the locomotive in response to a remote control signal comprising a unique identifier; an operator control unit (OCU) remote from the locomotive for generating the remote control signal, wherein the OCU further comprises: a first power source; a second power source; and a circuit for providing power to a volatile memory portion of the OCU from the second power source to maintain the unique identifier in the volatile memory while the first power source is being refreshed.
 19. The system of claim 18, wherein the second power source comprises one of a capacitor, a long-term storage battery and a solar panel.
 20. The system of claim 18, further comprising: a first battery; a second battery; a mechanism providing access to only one of the first battery and the second battery at a time; and a switch responsive to a position of the mechanism for switching power for the OCU from the first battery to the second battery. 